The present invention relates to a new apparatus and heat exchanger configuration useful in heating and cooling structures and generally in many heat transfer applications. More specifically, the present invention relates to a heat exchanger apparatus which functions both as a heat exchanger and a heat storage apparatus.
The most commonly used configuration (such as shell-tube heat exchangers) for heat transfer apparatus involving the use of an energy storage material is the apparatus shown in FIG. 1B with the heat exchanger conduits submerged in a zone filled with such a material. The arrangement of the tube in the actual exchanger might be a straight bank of tubes or a serpentine coil. This configuration has the disadvantage that the heat transfer surface area is limited unless a large number of tubes or finned-shaped tubes are used. Both of these options will increase the cost of the heat exchanger.
Another known configuration for energy storage material heat exchangers is that shown in FIG. 1C which is also described in U.S. Pat. No. 4,250,958 to Wasserman, issued Feb. 17, 1981. In this configuration, the storage material fills the annular space and the heat transfer fluid passes through the center of the conduit. This configuration suffers from the disadvantage that, although there is a large heat transfer capacity, the storage capacity is small.
The present invention has the following advantages:
1. It has a high heat transfer surface area to volume ratio which is accomplished by the zone storage configuration.
2. For the same heat transfer surface area, the device of the present invention has a significantly larger energy storage material storage capacity than conventional shell-tube heat exchangers and the other heat exchangers discussed above.
3. The device can be used with both gaseous and liquid heat transfer fluids.
4. There is a low pressure drop because of the use of straight tubes rather than spiral or serpentine coils.
5. Shipping and installation costs are reduced because the device can be filled with the storage material after installation. The unit can be manually handled without heavy equipment.